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C—CHEMISTRY; METALLURGY

C07—ORGANIC CHEMISTRY

C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS

C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms

C07C2/54—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition of unsaturated hydrocarbons to saturated hydrocarbons or to hydrocarbons containing a six-membered aromatic ring with no unsaturation outside the aromatic ring

C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms

C07C2/86—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon

C07C2/862—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms

B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00

B01J2229/30—After treatment, characterised by the means used

B01J2229/42—Addition of matrix or binder particles

Abstract

Alkylatable aromatic hydrocarbons are alkylated with olefins and alkylhalides under anhydrous alkylating conditions in the presence of certain metallic cation exchanged synthetic hectorite-type catalysts in which the metallic cation has a Pauling electronegativity greater than 1.0 and in which the central octahedral layer contains one or more divalent metals which have an ionic radius not greater than 0.75 A. In a specific embodiment, 1-dodecene is reacted with benzene by contacting the dodecene and benzene under anhydrous alkylating conditions in the liquid phase at the boiling point of the mixture with a catalyst comprising a metallic cation such as Al3-, In3- and Cr3- exchanged onto the surface of a synthetic nickeliferous hectorite.

This invention relates to a process for the liquid phase alkylation of aromatic hydrocarbons in which the catalyst comprises certain cation-exchanged synthetic hectorite-type clays. More particularly, the present invention is concerned with a method wherein an aromatic hydrocarbon, e.g. benzene, and an alkylating agent, e.g. an olefin, are reacted in the liquid phase in the presence of a catalyst which comprises a synthetic hectorite-type mineral which has a metal cation having a Pauling electronegativity greater than 1.0 in ion-exchange positions on the surface of the clay particles, and in which the central octahedral layer contains one or more divalent metals having an ionic radius not greater than 0.75 A as more particularly described hereinafter. Alkylated aromatic hydrocarbons have many uses dependng on their molecular weight and structure. Thus low molecular weight alkylbenzenes are useful in high octane gasolines and high molecular weight alkylbenzenes are useful as intermediates in the production of a alkylbenzene sulfonate detergents.

I have now found that certain synthetic trioctahedral 2:1 layer-lattice smectite-type minerals, particularly certain synthetic hectorite-type minerals, which have had their exchangeable cations replaced with a metallic cation having a Pauling electronegativity greater than 1.0 are effective catalysts for the alkylation of alkylatable aromatic hydrocarbons, e.g. benzene, with an olefin or alkyl halide under anhydrous alkylating conditions in the liquid phase.

Accordingly, it is an object of this invention to provide a process for alkylating in the liquid phase an alkylatable aromatic hydrocarbon with an olefin or alkyl halide under anhydrous alkylating conditions in the presence of certain synthetic hectorite-type catalysts in which the central octahedral layer contains one or more divalent metals having an ionic radius not greater than 0.75 A and which has in its cation exchange positions a metallic cation having a Pauling electronegativity greater than 1.0. It is another object of this invention to provide a method of alkylating aromatic hydrocarbons which comprises contacting in the liquid phase an alkylatable aromatic hydrocarbon with an olefin or alkyl halide in a reaction zone which is substantially free of water and in the presence of an effective amount of a catalyst, said catalyst comprising certain metallic cation exchanged synthetic hectorite-type clays wherein the metallic cation has a Pauling electronegativity greater than 1.0 and in which the central octahedral layer contains one or more divalent metals having an ionic radius not greater than 0.75 A. Another object is to provide a new catalyst which comprises a metallic cation exchanged synthetic hectorite-like clay in which the central octahedral layer contains one or more divalent metals having an ionic radius not greater than 0.75 A, provided that said octahedral layer contains less than 95 mole percent Mg, wherein the metallic cation has a Pauling electronegativity greater than 1.0. Other objects and advantages of this invention will become apparent to those skilled in the art upon reading the disclosure and the appended claims.

The catalyst of this invention comprises (1) a metallic cation which has a Pauling electronegativity greater than 1.0 exchanged onto the surface of (2) certain synthetic trioctahedral 2:1 layer lattice smectite-type minerals in which the central octahedral layer contains one or more divalent metals having an ionic radius not greater than 0.75 A as described hereinafter.

Representative metallic cations which are useful in this invention may be derived from the following metals, the Pauling electronegativity of which is given in parentheses (see "The Nature of The Chemical Bond" L. Pauling, 3rd Edition. 1960): Be (1.5), Mg (1.2), Al (1.5), Ga (1.6), In (1.7), Cu (1.9), Ag (1.9), La (1.1), Hf (1.3), Cr (1.6), Mo (1.8), Mn (1.5), Fe (1.8), Ru (2.2), Os (2.2), Co (1.8), Rh (2.2), Ir (2.2), Ni (1.8), Pd (2.2), Pt (2.2), and Ce (1.1). Preferred metallic cations are Al3+, In3+, Cr3+, and the rare earth cations, particularly La3+ and Ce3+. Mixtures of two or more metallic cations having a Pauling electronegativity greater than 1.0 may be present in the catalyst in cation exchange positions on the surface of the hectorite-type mineral.

Representative synthetic trioctahedral 2:1 layer-lattice smectite-type minerals which are useful in this invention are the structural analogs of hectorite in which the central octahedral layer contains one or more divalent metals having an ionic radius not greater than 0.75 A, provided that the metal is less than 95 mole % Mg, preferably less than 90 mole % Mg.

The charge-balancing cations of the hectorite-type minerals which can be used to prepare the catalysts of the present invention must be cations capable of being exchanged, preferably Na+, Li+, or NH4+, unless they are metallic cations which have a Pauling electro-negativity greater than 1.0.

The hectorite-type minerals useful in this invention can be synthesized hydrothermally. In general a gel containing the required molar ratios of the oxides or hydroxides of the metals desired to be incorporated into the central octahedral layer, silica, the charge balancing cations, and fluoride and having a pH of at least 8 is hydrothermally treated at a temperature within the range from 100°C - 325°C, preferably 250°C - 300°C, and preferably at the autogenous water vapor pressure for a period of time sufficient to crystallize the desired hectorite, generally 12 - 72 hours depending on the temperature of reaction. In general as the reaction temperature decreases the reaction time increases for well crystallized hectorite-type minerals. The hectorite-type minerals can be crystallized from melts of the oxides at very high temperatures, generally greater than 950°C. In these processes the charge balancing cation must be too large to be incorporated into the layer lattices, generally greater than 0.75 A, except that the charge balancing cation may be Li+. Preferably the charge balancing cation is Na+ or NH4+ since these are readily removed by cation exchange and replaced with the metallic cation as required in the present inventive process and catalyst.

where the cations in the parentheses are the cations present in the central octahedral layer, the two outer tetrahedral layers contain the Si cations, and R represents the charge-balancing cations exterior to the layer lattice of valence z. In the preferred catalysts of the present invention:

M is divalent cation selected from the group consisting of Mg, Ni, Co, Zn, Mn, Cu, and mixtures thereof, provided that M is less than 95 mole percent Mg(Mg<0.95(6-x)); R is at least one metallic cation which has a Pauling electronegativity greater than 1.0; and

0.33 ≦ x ≦ 1

0 ≦ y ≦ 4

More preferably 0 ≦ y ≦ 2 and M is selected from the group consisting of Mg, Ni, Co, and mixtures thereof.

The hectorite-type clays can contain minor amounts of other metals substituted isomorphously in the layer-lattices for the metals indicated in the above formulas, such as Fe2+ and Al3+ in the octahedral layer and Al3+, and Ge4+ in the tetrahedral layers. Metals having an ionic radius not greater than 0.75 A can be present in the octahedral layer. Metals having an ionic radius not greater than 0.64 A can be present in the tetrahedral layers. Generally the sum of such extraneous isomorphously substituted metals will amount to no more than 10 mole percent based on the metals present in the layer in which the substitution occurs.

The catalyst of the present invention can be prepared by any ion-exchange process wherein a metallic cation having a Pauling electro-negativity greater than 1.0 can be made to replace the exchangeable cation of the hectorite-type clay. Preferably an aqueous solution of a soluble salt of the desired metallic cation is admixed with the desired hectorite-type clay for a period of time sufficient to effect the desired exchange. Preferably an amount of metallic cation will be used which is from 100% to 500% of the exchange capacity of the hectorite-type clay, more preferably 100% to 300%. It is preferred to exchange at least 50% of the exchangeable cations of the clay with the metallic cations of this invention. It is also preferred to remove excess metallic cation salt and the soluble salt by-products of the exchange from the catlyst such as by filtration and washing prior to drying the catalyst. Alternatively the excess metallic cation salt and soluble salt by-product can be removed from the dried catalyst by slurrying the catalyst in an appropriate solvent, such as water or methanol, followed by filtration and re-drying. The exchange can also be conducted using a solution of the metallic cation salt in an appropriate organic solvents, such as methanol. Alternatively, the process disclosed in U.S. Pat. No. 3,725,528 can be used to prepare the catalyst.

The catalyst of this invention has been found to be active in catalyzing the reaction between alkylatable aromatic hydrocarbons and olefin-acting compounds under anhydrous alkylating conditions in the liquid phase.

Alkylatable aromatic hydrocarbons which can be used in the inventive process include benzene, toluene, xylene, the naphthalene series of hydrocarbons, etc. Any aromatic hydrocarbon can be alkylated if it has an unsubstituted carbon as long as steric hindrance does not prevent alkylation with the particular olefin-acting compound chosen for use in the process, and as long as the alkyl side chains on the aromatic ring do not prevent the aromatic compound from being adsorbed onto the layer-lattice surfaces of the catalyst. Benzene is the preferred aromatic hydrocarbon.

The process is carried out in the liquid phase utilizing a catalytically effective amount of the catalyst hereinbefore described. The catalyst can be used in amounts from 1% to 100% by weight based on the olefin-acting compound depending on the particular metallic cation-exchanged hectorite-type catalyst chosen for the reaction, the temperature of the reaction, and the length of time the catalyst has been in service. Preferably a concentration of catalyst from 2% to 50% by weight is used since this gives a relatively fast alkylation, still more preferably 2% to 10%.

The pressure can be elevated and is not critical as long as some of the olefin-acting compound can be kept dissolved in the liquid aromatic phase. Thus the pressure should be correlated with the temperature at which the reaction is being carried out in order to maintain the aromatic hydrocarbon in the liquid phase and to maintain a sufficient amount of olefin-acting compound dissolved therein to allow the alkylation reaction to proceed. Atmospheric pressure is preferred because of the simplicity of operations under atmospheric conditions.

The process is conducted at an elevated temperature since the rate of alkylation is undesirably low at room temperature. Preferably the temperature is in the range from 40°C to 200°C, more preferably 70°C to 150°C. It is desirable to conduct the process at the boiling point (reflux temperature) of the alkylatable aromatic hydrocarbon provided that it is in the above noted range. A non-alkylatable solvent, such as cyclohexane, can be used to provide the liquid alkylating medium and the temperature can conveniently be maintained at the boiling point of the solvent.

The molar ratio of alkylatable aromatic hydrocarbon to alkylating agent, i.e., the olefin-acting compound, can vary widely depending on the product desired. Thus at higher ratios such as 10 or above essentially only mono-alkylated product is obtained whereas at lower ratios the amount of polyalkylated product is increased. Preferably a molar ratio within the range from 3:1 to 20:1 will be used, more preferably 5:1 to 10:1.

It is important to maintain the reaction system free of water since water has a deactivating effect on the catalyst. Thus the catalyst must be dried before use. This may conveniently be done by removing the water from the catalyst at a low temperature, i.e., less than about 200°C. Alternatively the water may be removed by azeotropic distillation from a mixture of the catalyst in the alkylatable aromatic hydrocarbon or the solvent to be used in the reaction. This method will also remove any water in these organic systems and is preferred. The term "anhydrous" as used in this specification and in the claims is intended to mean that any free water which is present in the catalyst or the organic components present in the reaction mix is removed from the reaction system.

The following non-limiting examples are given in order to illustrate the invention.

EXAMPLES 1 - 27

Various cation exchanged forms of the natural mineral hectorite were prepared as follows: The exchange cation salt was dissolved in 500 to 750 ml. of methanol. Hectorite clay which had been previously dispersed in water, centrifuged, and spray dried in order to obtain the purified clay, was mixed in this salt solution at a concentration of 300 milliequivalents of cation per 100 grams of clay. This mixture was allowed to stand for approximately 20 hours before it was filtered. The filter cake was re-dispersed in 500 - 750 ml. of methanol followed by filtration for a total of three successive washings. The cation exchanged hectorite was then air dried for 20 hours at room temperature followed by oven drying at 105°C for 2 hours. The clay obtained by this process was very fine and needed no grinding. In the case of Ag+-hectorite, 10 ml. of concentrated nitric acid was added to the methanol solution before adding the clay to the solution, in order to prevent oxide formation of hydrolysis of the Ag+.

These cation exchanged hectorite clays were evaluated as catalysts for the alkylation of benzene using the following procedure: 10 grams of the cation exchanged hectorite and 200 - 250 ml. of benzene are refluxed in a round bottom flask equipped with a Dean-Stark tube attached to remove, azeotropically, sorbed water from the clay. After 2 - 4 hours the tube was removed and the reflux condenser rinsed with methanol and air dried to remove any residual moisture trapped in the condenser. 10 grams of the alkylating agent were added to the flask and the mixture refluxed with stirring for 24 hours. The clay was removed by filtration and washed with 100 ml. of benzene. The benzene was removed from the filtrate by vacuum evaporation leaving a product of unreacted alkylating agent and/or alkylbenzene. This product was then weighed and analyzed by either infrared spectrophotometry, refractometry, or gas chromatography to determine the amount of alkyl-benzene formed. The cation exchanged hectorites evaluated and the data obtained are given in Table 1.

The data indicate that the natural hectorite clay containing exchanged metallic cations having a Pauling electronegativity less than or equal to 1.0 were ineffective as catalysts for the alkylation of benzene. Metallic cations having a Pauling electronegativity greater than 1.0 were effective catalysts when exchanged onto hectorite. These include Be2+ and Mg2+ (Group IIA), Al3+ and Im3+ (Group IIIA), La3+ (Group IIIB), Cr3+ (Group VIA), Mn2+ (Group VIIB), Fe3+, Co2+, Ni2+ and Pd2+ (Group VIII), Cu2+ and Ag+ (Group IB), and Ce3+ (rare earths). The effect of moisture within the reaction zone on the activity of certain of the catalysts can be ascertained by reference to the data for Examples 1, 4 and 6. The small amount of water which remained in the reflux condenser (Examples 1,6) or in the atmosphere (Example 4) was sufficient to decrease the activity of Al3+ -exchanged hectorite approximately 50%, whereas In.sup. 3+ -exchanged hectorite was very active in the presence of such small quantities of water.

Several cation exchanged hectorites were prepared by at least one of the following procedures as indicated in Table 2: Process A -- exchange in methanol solution as in Examples 1 - 27; Process B -- exchange in aqueous solution substituting water for methanol in Process A except in the last washing step; Process C -- exchange in aqueous solution, no washing. These catalysts were evaluated for the alkylation of benzene by 1-dodecene at a 1-dodecene:catalyst weight ratio of 10:1 using the same process as in Examples 1-27. The percent conversion of the olefin after one hour is given in Table 2. The catalysts used in Examples 33, 34, 37 and 38 were the same catalysts used in Examples 32, 33, 36 and 37 respectfully, after rinsing them with benzene.

The data indicate that water is the preferred solvent for the metallic cation salt, i.e., for the exchange solution, and that the catalyst should be washed to remove soluble salts from the catalyst. The catalyst can be re-used after rinsing with benzene to remove adsorbed products from the catalyst.

An Al3+ -exchanged hectorite and a Cr3+ -exchanged hectorite (purified natural clay as in Examples 1 - 27) were prepared by the aqueous exchange process B of Examples 28 - 43. These clays were evaluated as catalysts for the alkylation of benzene by 1-dodecene at various mole ratios of benzene to dodecene and/or various weight ratios of dodecene to catalyst as indicated in Table 3. The percent conversion of dodecene after 1 hour and, in some cases, 24 hours using the same process as in Examples 1 - 27 was determined. The data obtained are given in Table 3.

The data indicate that these exchanged clays were excellent catalysts at concentrations of exchanged clay greater than about 2%, based on the weight of dodecene, although concentrations as low as 1% converted most of the dodecene in 24 hours.

A synthetic hectorite-type clay was prepared by reacting at a temperature of 350°C in a Ag-lined stainless steel autoclave under the autogenous water vapor pressure created in the autoclave for 48 hours a composition having the molar formula:

the product obtained, after drying at 105°C, had x-ray diffraction peaks at 12.5 A and 1.517 A which indicates that the product was a well crystallized hectorite-type clay. The expected formula for this nickleferous hectorite is:

This synthetic hectorite-type clay mineral was exchanged to the Al3+ -form as follows: the dried clay was mixed into an aqueous AlCl.sub. 3 solution at a concentration of 300 milliequivalents of Al3+ per 1003 grams of clay. The mixture was allowed to stand for approximately 20 hours before it was filtered. The filter cake was re-dispersed in 500-750 ml. of deionized water followed by filtration for a total of two successive washings. Thereafter another washing was undertaken substituting methanol for the deionized water. The Al3+ -cation exchanged hectorite-type clay was then air dried for 20 hours at room temperature followed by oven drying at 105°C for 2 hours. The catalyst obtained by this process was very fine and needed no grinding.

The Al3+ -exchanged synthetic hectorite-type clay was evaluated as follows: 1 gram of the clay and 200-500 ml. of benzene were refluxed in a round bottom flask equipped with a Dean-Stark tube attached to remove, azeotropically, sorbed water from the clay. After 2-4 hours the tube was removed and the reflux condenser rinsed with methanol and air dried to remove any residual moisture trapped in the condenser. 10 grams of 1-dodecene were then added to the flask and the mixture refluxed with stirring.

After 1 hour a sample was taken and analyzed by gas chromatographic analysis. 21.1% of the 1-dodecene was converted to dodecylbenzene and 9.8% of the 1-dodecene was converted to heavy alkylate. After 24 hours another sample was taken and analyzed. 67.5% of the 1-dodecene was converted to dodecyclbenzene and 15.8% of the 1-dodecene was converted to heavy alkylate.

EXAMPLE 56

A synthetic hectorite-type clay was prepared by the process of Example 55 starting with a composition having the molar formula:

the product obtained, after drying at 105°C, had x-ray diffraction peaks at 12.7 A and 1.522 A which indicates that the product was a well crystallized hectorite-type clay. The expected formula for this cobaltiferous hectorite is:

This synthetic hectorite-type clay was exchanged to the Al3+ -form and evaluated as in Example 55. 48.1% of the 1-dodecene was converted to dodecyclbenzene and 8.7% of the 1-dodecene was converted to heavy alkylate after 24 hours refluxing.

It will be understood that while I have explained the invention with the aid of specific examples, nevertheless considerable variation is possible in choice of raw materials, proportions, processing conditions, and the like, within the broad scope of the invention as set forth in the claims which follow. Thus, for example, my inventive catalyst may be used simultaneously with other catalytic materials so as to suit particular conditions and circumstances.

Claims (5)

I claim:

1. A catalyst comprising a synthetic hectorite-type clay containing a metallic cation having a Pauling electronegativity greater than 1.0 in cation exchange positions on the surface of said clay, said catalyst having the following structural formula: